Carbohydrates which contain a plurality of hydroxy substituents will be defined in the following specification and appended claims as polyols. The carbohydrates which may be classified as monosaccharides or polysaccharides are generally found in nature. Some of the carbohydrates possess desirable characteristics which enable them to be utilized for a wide variety of purposes in industry. For example, glucose or fructose are widely used as sweetening agents in confections, food stuffs, etc. Other carbohydrates or polyols such as sorbitol which is the polyol reduction product obtained from glucose may be used for the synthesis of resins, surface active agents, varnishes, in explosive manufacture, etc. While the carbohydrates such as monosaccharides which may contain from 4 to about 6 carbon atoms such as tetroses, pentoses, hexoses, etc. as well as polysaccharides such as starch, cellulose, etc. are widely found in nature and are therefore relatively inexpensive to obtain, lower polyols or diols are also useful in many industries.
As an example of lower polyols which are useful in industry, glycerol is a prime illustration. This compound may be used in alkyd resins, explosives, in pharmaceutical compounds, in perfumery, cosmetics, as a preservative or sweetening agent in foodstuffs, as a solvent, emulsifying agent, binder for cements and mixes, as an antifreeze agent, as a lubricant and softener, as a bacteriostat, humectant, etc. Glycerol may be prepared from the spent lye liqueur from the saponification of fats and oils in the soap industry, by precipitation of salt, albumin oils, and catalytic soaps of the higher fatty acids utilizing iron persulfate or aluminum sulfate in concentration with a subsequent steam distillation. Another method of preparing glycerol is by the chlorination and hydrolysis of propylene or allyl alcohol; or by the reaction of acrolein and hydrogen peroxide followed by reduction of the glyceraldehyde. Another polyol which finds a wide variety of uses is ethylene glycol which, like glycerol, may also be used as an antifreeze, as a coolant in motors, in the manufacture of explosives, as a dye solvent, in the manufacture of lacquers, resins, printing inks, etc. This compound has been prepared by heating ethylene chlorohydrin with a solution of an alkali carbonate or bicarbonate; by the oxidation of ethylene with air followed by hydration of the ethylene oxide which is formed or from the reaction of formaldehyde, water and carbon monoxide to form glycolic acid followed by hydrogenation to obtain the desired product.
It is readily apparent that the lower polyols such as those described are important articles of commerce, being widely used in a variety of chemical industries. However, processes for obtaining these polyols have been relatively complicated in nature and usually involve a number of steps in the process in order to obtain a desired product. As will hereinafter be shown in greater detail, it has now been discovered that lower polyols may be obtained by hydrocracking a higher polyol in the presence of certain catalytic compositions of matter which will permit the recovery of the desired products in a greater yield than has heretofore been provided.